1. Field of the Invention
The embodiments of the present invention relate to an apparatus and a method for removing blooming of a camera image.
2. Discussion of the Related Art
As illustrated in FIG. 1, a monitoring camera is located in a specific area, captures an image and outputs the captured image to a digital video recorder (DVR). The DVR stores the captured image as a data file in a recording medium such as a hard disc and/or displays the captured image on the screen of a monitor. An operator who operates the DVR monitors images captured by the monitoring camera through the monitor in real time or reproduces data files stored in the recording medium to observe or monitor previously captured images.
The camera may have a backlight function or a backlight compensation function. When a very bright object or a light source exists in an image captured by the camera in a backlight compensation mode, the camera performs a backlight compensation operation for compensating exposure, which further opens its iris to increase the quantity of light input to an image-capturing element such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), or increases amplification gain of a signal output from the image-capturing element, such that a relatively dark object around the light source or the bright object can be identified.
When the backlight compensation operation is performed, the luminance level of a low luminance region increases, and thus a user can normally recognize the dark object. However, the luminance level of a high luminance region also increases to generate blooming that makes the bright object seem saturated by light.
For instance, when the camera photographs the front side of a car in a normal status, numbers on a number plate are normally seen, as illustrated in FIG. 2. When the head light of the car is turned on, however, the luminance of the number plate located besides the head light is relatively low in comparison, and thus the numbers on the number plate are less visible.
Accordingly, when a high luminance region and a low luminance region exist together in an image, the camera determines that the current status thereof corresponds to a backlight status and performs the backlight compensation operation to open the iris and increase the gain. At this time, both the luminance level of the low luminance region and the luminance level of the high luminance region increase, and the luminance level of the high luminance region, such as the headlight of the car, excessively increases to result in a blooming phenomenon that cause regions around the head light to be seen as irregular white regions, as illustrated in FIG. 2. Consequently, the numbers on the number plate cannot be easily identified.